The present invention relates to hand held folding knives, and more specifically folding knives which have a locking mechanism for engaging the blade to prevent the blade from inadvertently closing.
Pocket multi-tools and pocket knives are commonly used by sportsmen, craftsmen and others who desire a compact, portable blade or tool. Unfortunately, many of the implements or blades commonly associated with these types of pocket knives and multi-tools do not have locking mechanisms to prevent the blades from inadvertently closing. Thus, the folding knife or multi-tool can be potentially dangerous to use if a sharpened blade or other implement inadvertently closes.
More recently, locking devices have been incorporated into folding knives and multi-tools to engage the blade with a locking mechanism to prevent the inadvertent closing of the knife blade. One type of locking mechanism known in the art is a xe2x80x9cliner lockxe2x80x9d which utilizes a leaf spring positioned within the cavity of the knife handle and which engages the heel end of the knife blade. The blade is typically released by the user by applying finger pressure to the leaf spring, thus releasing the leaf spring from the knife blade.
Another commonly used folding knife locking mechanism is a xe2x80x9cback lockxe2x80x9d, which utilizes a locking bar positioned along an upper edge of the knife handle. When finger pressure is applied to the locking bar, a tang interconnected to the locking bar is withdrawn from a cut-out xe2x80x9canvilxe2x80x9d portion which is positioned proximate the heel end of the blade. When the tang is released, the knife blade is allowed to rotate between a first extended position of use and a second closed position wherein at least a portion of the knife blade is stored within a cavity in the knife handle.
Unfortunately, with both liner locks and back lock locking mechanisms, it is possible for the locking apparatus, to potentially become disengaged from the blade after excessive and continuous use. Further, the positioning of the liner lock and back lock are often difficult to locate with a user""s fingers and thus not ergonomically user friendly, and cannot be accessed on both a front and rear side of the knife handle.
Thus, there is a need for an improved folding knife locking mechanism which is simplistic to construct, uses a minimum number of components and is extremely reliable to prevent the inadvertent closure of the knife blade. There is an additional need for a locking mechanism which is positioned to allow quick and easy access by one or more of a user""s fingers on both sides of the knife handle.
It is thus an aspect of the present invention to provide a locking mechanism for a folding knife or multi-tool which is positioned immediately opposite a user""s thumb or fingers and which is thus immediately accessible for selective opening. Thus, in one embodiment of the present invention the lock release mechanism is positioned immediately adjacent to a user""s thumb or finger, and may be accessed on both sides of a folding knife handle.
It is a further aspect of the present invention to provide a locking mechanism which has a biasing means which continually biases the locking mechanism to secure the blade while it is in an extended position, and thus cannot be inadvertently closed. Thus, to release the blade the locking mechanism must be engaged by a user""s thumb or finger and pushed in a rearward direction by the user, thus making it substantially impossible for the knife locking mechanism to fail. Alternatively, the locking mechanism may be oriented in numerous different directions to accommodate certain handle and blade designs, and may be used without any type of biasing means. In these embodiments, the locking mechanism can be engaged or disengaged with the tang of the folding knife blade by means of gravity or by pressure from a user""s fingers.
It is yet another object of the present invention to provide a blade locking mechanism which is simplistic to use, cost effective to manufacture and requires a minimum number of components which are not susceptible to failure after repeated use. Thus, in one embodiment of the present invention a substantially spherical ball is used in conjunction with a biasing means which is positioned within a slot in the knife handle to selectively lock the blade in a first extended position of use, and thus requires only two major components, including the substantially spherical ball and an elongated slot which houses the substantially spherical ball. The substantially spherical ball, as used herein is meant to include all shapes that are round, oval, semi-round, semi-oval, cylindrical, combinations therein, or other feasible shapes which can travel within the elongated slot in the knife handle.
It is a further aspect in one embodiment of the present invention that the elongated slot be oriented with respect to the tang to support the substantially spherical ball in a xe2x80x9cmorsexe2x80x9d type taper, and thus has a greater diameter near the outer edge of the tang than the forward portion of the tang. Preferably, this taper is between about 2-20 degrees, and allows the substantially spherical ball to properly seat between the tang and the elongated slot even after extensive wear to the substantially spherical ball, the tang or the elongated slot.
Thus, in one aspect of the present invention, a folding knife with a substantially spherical locking mechanism is provided, comprising: